A tablet computing device (or a similar type of embedded device) often contains a touchscreen that allows a user to enter data into the device. Data entry by the user may be done using a finger or a stylus (or pen). Input from the pen (or finger) to the device is called “ink.”
Ink is digitized to allow it to be processed and manipulated by the computing device and displayed. This typically is performed by sending out the digitized ink to the operating system on the device, having the processor process the ink, and then sending the processed ink to a graphics card. The graphics card then renders the ink (which is the effect of the user's action) on a monitor or display.
One deficiency of current ink rendering techniques is the latency introduced. Pens and fingers tend to be fast and virtually instantaneous while the rendering of the ink tends to lag. In fact, the entire ink rendering process can introduce a latency that can be on the order of anywhere between 50 to 100 milliseconds or even greater. This latency in ink rendering can make for a slow and awkward user experience.
In particular, this latency is an undesirable effect in that is breaks the perceptive barrier of manipulating an object directly. Of course these are mostly perceived in situations where there is a co-located experience. In other words, when the input and the output are co-located with each other (such as writing with a stylus on a tablet computing device or a touchscreen), the latency effect is greatest.